cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A223026 G.f. A(x) satisfies: A(x)^8 = A(x^2)^4 + 8*x.

Original entry on oeis.org

1, 1, -3, 14, -76, 441, -2678, 16813, -108093, 707451, -4696017, 31530792, -213715953, 1460072247, -10042361784, 69473047716, -483046768116, 3373552141194, -23653214175084, 166422650191122, -1174621198245837, 8314055808436788, -58998774106863513
Offset: 0

Views

Author

Paul D. Hanna, Mar 11 2013

Keywords

Comments

The limit a(n+1)/a(n) seems to be near -7.46...

Examples

			G.f.: A(x) = 1 + x - 3*x^2 + 14*x^3 - 76*x^4 + 441*x^5 - 2678*x^6 +-...
where
A(x)^8 = 1 + 8*x + 4*x^2 - 6*x^4 + 24*x^6 - 117*x^8 + 612*x^10 - 3426*x^12 +-...
A(x^2)^4 = 1 + 4*x^2 - 6*x^4 + 24*x^6 - 117*x^8 + 612*x^10 - 3426*x^12 +-...
A(x)^2 = 1 + 2*x - 5*x^2 + 22*x^3 - 115*x^4 + 646*x^5 - 3822*x^6 +-...
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x); for(i=1, #binary(n), A=(subst(A, x, x^2)^4+8*x+x*O(x^n))^(1/8)); polcoeff(A, n, x)}
    for(n=0, 20, print1(a(n), ", "))

Formula

Self-convolution yields A228711.

A187814 G.f. A(x) satisfies: 1/A(x)^2 + 4*x*A(x)^2 = 1/A(x^2) + 2*x*A(x^2).

Original entry on oeis.org

1, 1, 6, 41, 334, 2901, 26651, 253709, 2483395, 24829132, 252506507, 2603798287, 27161758393, 286118173600, 3039211373800, 32517513415886, 350122302629869, 3790909121211262, 41249405668333107, 450832515809731316, 4947009705400704588, 54479711308604703264, 601933495810972446631
Offset: 0

Views

Author

Paul D. Hanna, Aug 30 2013

Keywords

Examples

			G.f.: A(x) = 1 + x + 6*x^2 + 41*x^3 + 334*x^4 + 2901*x^5 + 26651*x^6 +...
such that A(x) satisfies the identity illustrated by:
1/A(x)^2 + 4*x*A(x)^2 = 1 + 2*x - x^2 + 2*x^3 - 5*x^4 + 12*x^5 - 30*x^6 +...
1/A(x^2) + 2*x*A(x^2) = 1 + 2*x - x^2 + 2*x^3 - 5*x^4 + 12*x^5 - 30*x^6 +...
Related expansions.
A(x)^2 = 1 + 2*x + 13*x^2 + 94*x^3 + 786*x^4 + 6962*x^5 + 64793*x^6 +...
A(x)^4 = 1 + 4*x + 30*x^2 + 240*x^3 + 2117*x^4 + 19512*x^5 + 186706*x^6 +...
1/A(x) = 1 - x - 5*x^2 - 30*x^3 - 233*x^4 - 1949*x^5 - 17503*x^6 +...
1/A(x)^2 = 1 - 2*x - 9*x^2 - 50*x^3 - 381*x^4 - 3132*x^5 - 27878*x^6 +...
The g.f. of A107086 begins:
F(x) = 1 + x - x^2 + 2*x^3 - 5*x^4 + 13*x^5 - 35*x^6 + 99*x^7 - 289*x^8 +...
where F(x)^4 = F(x^2)^2 + 4*x:
F(x)^2 = 1 + 2*x - x^2 + 2*x^3 - 5*x^4 + 12*x^5 - 30*x^6 + 82*x^7 - 233*x^8 +...
F(x)^4 = 1 + 4*x + 2*x^2 - x^4 + 2*x^6 - 5*x^8 + 12*x^10 - 30*x^12 + 82*x^14 +...
		

Crossrefs

Cf. A107086.
Cf. variants: A228712, A228928.

Programs

  • PARI
    {a(n)=local(A=1+x+x*O(x^n)); for(i=1, n, A=1/(1/subst(A, x, x^2) + 2*x*subst(A, x, x^2) - 4*x*A^2 +x*O(x^n))^(1/2)); polcoeff(A, n)}
    for(n=0, 30, print1(a(n), ", "))

Formula

G.f. A(x) satisfies:
(1) 1/A(x)^2 + 4*x*A(x)^2 = F(x)^2,
(2) 1/A(x^2) + 2*x*A(x^2) = F(x)^2,
(3) A(x) = ( (F(x)^2 - sqrt(F(x)^4 - 16*x)) / (8*x) )^(1/2),
(4) A(x^2) = (F(x)^2 - sqrt(F(x)^4 - 8*x)) / (4*x),
where F(x) = (F(x^2)^2 + 4*x)^(1/4) is the g.f. of A107086.

A228711 G.f. A(x) satisfies: A(x)^4 = A(x^2)^2 + 8*x.

Original entry on oeis.org

1, 2, -5, 22, -115, 646, -3822, 23496, -148368, 955822, -6256273, 41480668, -277954706, 1879118354, -12800031737, 87758481546, -605091552753, 4192829686338, -29180958305391, 203887504096188, -1429568781831693, 10055261467844862, -70929518958227340
Offset: 0

Views

Author

Paul D. Hanna, Aug 30 2013

Keywords

Examples

			G.f.: A(x) = 1 + 2*x - 5*x^2 + 22*x^3 - 115*x^4 + 646*x^5 - 3822*x^6 +...
where A(x)^4 = A(x^2)^2 + 8*x as demonstrated by:
A(x)^2 = 1 + 4*x - 6*x^2 + 24*x^3 - 117*x^4 + 612*x^5 - 3426*x^6 + 20184*x^7 +...
A(x)^4 = 1 + 8*x + 4*x^2 - 6*x^4 + 24*x^6 - 117*x^8 + 612*x^10 - 3426*x^12 +...
The g.f. of A228712 begins:
G(x) = 1 + 3*x + 72*x^2 + 2307*x^3 + 86295*x^4 + 3513477*x^5 +...
and satisfies: sqrt(1/G(x^2)^2 + 4*x*G(x^2)^2) = A(x).
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x); for(i=1, n, A=(subst(A, x, x^2)^2+8*x+x*O(x^n))^(1/4)); polcoeff(A, n, x)}
    for(n=0, 20, print1(a(n), ", "))

Formula

G.f. A(x) satisfies:
(1) A(x) = sqrt(1/G(x^2)^2 + 4*x*G(x^2)^2),
(2) sqrt(A(x^2)^2 + 4*x) = 1/G(x^4) + 2*x*G(x^4),
where G(x) is the g.f. of A228712.
Self-convolution of A223026.

A228928 G.f. A(x) satisfies: 1/A(x)^8 + 64*x*A(x)^8 = 1/A(x^2)^4 + 8*x*A(x^2)^4.

Original entry on oeis.org

1, 7, 672, 91147, 14486409, 2516759469, 463051052653, 88674496050245, 17490154693966234, 3528922457876864195, 724934544034900295558, 151110852750623222310189, 31881833636363854856989129, 6795336519252277650628254056, 1461001691259055273207790036665
Offset: 0

Views

Author

Paul D. Hanna, Sep 08 2013

Keywords

Examples

			G.f.: A(x) = 1 + 7*x + 672*x^2 + 91147*x^3 + 14486409*x^4 +...
such that A(x) satisfies the identity illustrated by:
1/A(x)^8 + 64*x*A(x)^8 = 1 + 8*x - 28*x^2 + 224*x^3 - 2198*x^4 + 23856*x^5 +...
1/A(x^2)^4 + 8*x*A(x^2)^4 = 1 + 8*x - 28*x^2 + 224*x^3 - 2198*x^4 + 23856*x^5 +...
Related expansions.
A(x)^4 = 1 + 28*x + 2982*x^2 + 422408*x^3 + 68709025*x^4 + 12111355116*x^5 +...
A(x)^8 = 1 + 56*x + 6748*x^2 + 1011808*x^3 + 169965222*x^4 + 30589656944*x^5 +...
1/A(x)^4 = 1 - 28*x - 2198*x^2 - 277368*x^3 - 42560861*x^4 - 7240234148*x^5 +...
1/A(x)^8 = 1 - 56*x - 3612*x^2 - 431648*x^3 - 64757910*x^4 - 10877750352*x^5 +...
The g.f. of A228927 satisfies F(x) = (F(x^2)^8 + 16*x)^(1/16) and begins:
F(x) = 1 + x - 7*x^2 + 70*x^3 - 798*x^4 + 9737*x^5 - 124124*x^6 + 1631041*x^7 +...
where F(x)^16 = F(x^2)^8 + 16*x:
F(x)^8 = 1 + 8*x - 28*x^2 + 224*x^3 - 2198*x^4 + 23856*x^5 - 277368*x^6 +...
F(x)^16 = 1 + 16*x + 8*x^2 - 28*x^4 + 224*x^6 - 2198*x^8 + 23856*x^10 +...
		

Crossrefs

Cf. A228927.
Cf. variants: A187814, A228712.

Programs

  • PARI
    {a(n)=local(A=1+x+x*O(x^n)); for(i=1, n, A=1/(1/subst(A, x, x^2)^4 + 8*x*subst(A, x, x^2)^4 - 64*x*A^8 +x*O(x^n))^(1/8)); polcoeff(A, n)}
    for(n=0, 20, print1(a(n), ", "))

Formula

G.f. A(x) satisfies:
(1) 1/A(x)^8 + 64*x*A(x)^8 = F(x)^8,
(2) 1/A(x^2)^4 + 8*x*A(x^2)^4 = F(x)^8,
(3) A(x) = ( (F(x)^8 - sqrt(F(x)^16 - 256*x)) / (128*x) )^(1/8),
(4) A(x^2) = ( (F(x)^8 - sqrt(F(x)^16 - 32*x)) / (16*x) )^(1/4),
where F(x) = (F(x^2)^8 + 16*x)^(1/16) is the g.f. of A228927.
Showing 1-4 of 4 results.